Numerous liberated slaves found themselves forced to accept low-paying jobs on the lands of their previous masters. (Apex)
I came across this; please inform me if this is the wrong subject. Old Pali documents suggest the existence of some trade routes that were operational at least 2500 years ago.
The answer is C) The country had a low population density and lacked any defense system.
The ease with which European imperialists conquered China was due to its sparse population and absence of defense mechanisms.
During that time, China did not possess a formal or adequately trained military.
These aspects made it easier for invaders to penetrate Chinese lands, despite the challenging geography which included mountainous regions that had kept China isolated for many years. The Mongols invaded and controlled significant parts of China in the 1120s AD, and another instance of invasion was the Japanese occupation between 1937 and 1945.